The correct answer is - C. European leaders felt imperialism would improve the economy.
The leaders of the strong European nations felt that the imperialism would be an excellent method to boost significantly the economies of their nations. The reason for that was that the countries that were less developed provided free natural resources, very cheap labor force, and also market for the manufactured products, if conquered of course. The European colonial countries used the opportunity to the maximum, controlling most of the world, having enormous amounts of natural resources on disposal, and very large market for their products, resulting in significant increase of wealth, influence, and development.